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wse - Websockets for Erlang
===========================
WSE is a simple, standalone, websocket server which execute
request in the browser instead of in the web server. There is a bit
of boot strapping that may need help from a web server. But a simple
web page and a browser is all that it takes to get running.
To get control of part of a web page (or all of it) use the following
HTML snippet. Also make sure you have ej.js and wse.js in the same directory.
<html><head>
<title>wse demo page</title>
<script src='ej.js'></script>
<script src='wse.js'></script>
<script>
window.onload = function() {
if (Wse.open("ws://localhost:1234/websession"))
Wse.start('wse_demo', 'run', ["myid"]);
};
</script></head>
<body>
<div id="myid"></div>
</body></html>
Next thing is to start erlang wse server (default to port 1234):
$ erl
> wse_server:start().
Then have the erlang module wse_demo in the path somewhere:
-module(wse_demo).
-export([run/2]).
run(Ws, Where) ->
ElemNode = wse:createElement(Ws, "p"),
TextNode = wse:createTextNode(Ws, "Hello world"),
wse:appendChild(Ws, ElemNode, TextNode),
wse:appendChild(Ws, wse:id(Where), ElemNode).
The browser will call wse_demo:run (via the websocket) with the web socket proxy process as a the first argument and the "myid" as the second argument. From thereon the web page can be manipulated at will.
# register pages
One nice trick to interact with pages from command line is to
register the page it self
<html><head>
<title>Page A</title>
<script src='ej.js'></script>
<script src='wse.js'></script>
<script>
window.onload = function() {
if (Wse.open("ws://localhost:1234/websession")) {
Wse.register('page_a');
};
</script>
</head><body>
<p id="x">Hello A World</p>
</body></html>
Now this page should be registered in erlang and can be tested. Start with
changing the text in the paragraf on the page.
> {ok,X} = wse:getElementById(page_a, "x").
> {ok,Text} = wse:firstChild(page_a, X).
> wse:set(page_a, Text, "nodeValue", "Hej A").
Or we could send some ehtml (erlang style html) defining a button to it
> wse:send(page_a, "x", {button,[{id,"y"}],["Press Me"]}).
Or why not send a whole table to it
> wse:send(page_a, "x", {table,[],[{tr,[],[{td,[],["A"]},{td,[],["B"]}]},{tr,[],[{td,[],["C"]},{td,[],["D"]}]}]}).
To have events sent to us when pressing a button, using send, we can do
> {ok,E} = wse:create_event(page_a).
> wse:send(page_a, "x", {button,[{id,"y"},{onclick,"Wse.notify("++integer_to_list(E)++",'click');"}],["Press Me"]}).
Click on the button on page A a couple of times
> flush().
Shell got {notify,2,[],"click"}
Shell got {notify,2,[],"click"}
Shell got {notify,2,[],"click"}
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